1. Field of the Invention
This invention relates to probes for testing electrical devices and more particularly to testing of microelectronic devices.
2. Description of Related Art
Testing of circuits by means of spring probes is a highly developed technology. However, as the technology changes with ever decreasing dimensions of the devices being tested, problems arise.
Now there are a number of problems with the technology for testing of circuits among which are as follows:
1. Currently available spring probes are retained in holders which rotate in the guides causing damage to product pads. PA0 2. Contact integrity between the probes and the contact springs is poor. PA0 3. Probe-to-probe locations must be more accurate in current technical environment, in order to be able to contact the very accurate dense arrays of miniature product test pads. PA0 4. By design, state-of-the art spring plunger probes are contained in sleeves which increase the diameter of the package. This negates their use in applications where test features have very close center-to-center distances.
In accordance with this invention, several features are provided, as follows:
Testing probes in a testing apparatus are supported in a unitary structure to provide rigidity of the supports for the probes in testing.
The spring probes have a contact head at the distal end from the probe tip with a set of antirotation tabs which lock in a cooperating antirotation slot in the probe guide. The contact head has a cone-shaped pilot at its tip which is engaged with a gold-plated contact spring. The inner diameter is integrally in contact with the pilot by mechanical engagement or bonding by soldering or laser welding or the like. A method of forming a probe tip on an array of test probes in a support member for a test apparatus includes inserting a plurality of probes into an array of probe cylinders in the member with the ends of the probes extending below the ends of the cylinders, the probes being retained by fixturing means at a predetermined position in the cylinders, the ends of the probes are planarized to provide a smooth surface of the member with the probes flush therewith, apply a layer of resist to the lower surface of the member covering the guide plate and the newly planarized lower ends of the probes, after the resist has been exposed to a pattern through a high precision mask, a set of rings at the base of the planarized probes is formed in the resist by etching the tips through the resist, and then remove the fixturing means.